In order to have a reliable electrical connection between electrical contact terminal members such as pin and socket terminals, it is necessary to have at least one and preferably a plurality of contact points or lines between the pin and socket terminal members. This is particularly important for electrical terminal members used to carry power, wherein it is desirable to have multiple contact points between the mating terminal members to provide an equalized flow of current therethrough. In order to get an equalized current path, it is desirable that as many of the contact points as possible be in parallel.
One way of achieving a plurality of parallel points is by using members having a number of compliant beams or independent spring fingers. U.S. patent application Ser. No. 07/091,973 discloses one type of power contact terminal pair wherein the female terminal member includes a plurality of cantilevered beams received in a solid receptacle member, thus providing a plurality of contact points between the two terminal members when they are mated. U.S. Pat. Nos. 3,453,587; and 4,039,238 disclose connector assemblies in which a strip of interconnected contact springs is disposed in a tubular array around the peripheral surface of one of the mating terminal members to provide a plurality of contact points between the members.
Another type terminal assembly that assures electrical contact between mated members is a tapered pin and receptacle assembly members such as those disclosed in U.S. Pat. Nos. 3,281,763; and 3,372,476 owned by the present assignee, wherein a solid pin terminal includes a tapered forward contact surface that engages and is wedged against a complimentary surface within a taper pin receptacle. The advantage of a taper pin is that it has a low value of constriction resistance when the contact is mated. To ensure electrical engagement, tapered terminals are typically designed to "self lock" upon application of sufficient force. A tool and application of force are therefore required to disengage the locked members. Furthermore, the presence of dust in the tapered area can reduce the efficiency of the contact and prevent self locking.
It is desirable therefore, particularly in power connection to provide a terminal assembly that will have a low resistance and multiple contact points. It is also desirable that the connection be readily separable and not lock itself together.
High quality electrical engagement is critical particularly in power conducting terminal connections and is dependent not only on high contact force but also on the use of conductive materials such as copper and copper alloys. One problem associated with the highly conductive materials and load demands placed on power contacts is that there is generally a 20 to 30 degree rise in temperature when the contact is placed under load. Since a rise in temperature will cause the materials of the two contact members to expand and try to move axially apart. To retain continuity of the circuit path it is necessary to provide means wherein the pin and socket members remain securely engaged and have electrical contact in the multiple contact points. Typically this means included use of a "self-locking" taper or a pre-loaded spring member, that is a heavy duty spring member, which provides considerable force against a member of the assembly.